Re: [PATCH v8 06/15] x86: Add early SHA support for Secure Launch early measurements

Eric Biggers
2024-02-23T18:30:06Z

On Fri, Feb 23, 2024 at 06:20:27PM +0000, Andrew Cooper wrote:
> On 23/02/2024 5:54 pm, Eric Biggers wrote:
> > On Fri, Feb 23, 2024 at 04:42:11PM +0000, Andrew Cooper wrote:
> >> Yes, and I agree.  We're not looking to try and force this in with
> >> underhand tactics.
> >>
> >> But a blind "nack to any SHA-1" is similarly damaging in the opposite
> >> direction.
> >>
> > Well, reviewers have said they'd prefer that SHA-1 not be included and given
> > some thoughtful reasons for that. But also they've given suggestions on how to
> > make the SHA-1 support more palatable, such as splitting it into a separate
> > patch and giving it a proper justification.
> >
> > All suggestions have been ignored.
>
> The public record demonstrates otherwise.
>
> But are you saying that you'd be happy if the commit message read
> something more like:
>
> ---8<---
> For better or worse, Secure Launch needs SHA-1 and SHA-256.
>
> The choice of hashes used lie with the platform firmware, not with
> software, and is often outside of the users control.
>
> Even if we'd prefer to use SHA-256-only, if firmware elected to start us
> with the SHA-1 and SHA-256 backs active, we still need SHA-1 to parse
> the TPM event log thus far, and deliberately cap the SHA-1 PCRs in order
> to safely use SHA-256 for everything else.
> ---

Please take some time to read through the comments that reviewers have left on
previous versions of the patchset.

- Eric